I've just bought a 12V 260mA electromagnet and I have some questions about it
I don't know why, but when I connect electromagnet, my 12V power source (9V and 2 1.5V AA batteries in series) drops to 8V. I suspect that this is because of the protection of the 9V battery, because the 9V battery drops to 5V whereas voltage drop of 2 1.5V AA batteries is negligible, and when I try different 9V battery, it keeps and slowly drops to 2V.
When I disconnect the electromagnet, it seems that it sends reverse voltage, Before I disconnect, my multimeter connected in reverse reads around -8V, but when I disconnect it, it reads around 2V. Since I'm gonna switch electromagnet using transistor, would this reverse voltage be harmful? If so, just connecting the diode would prevent this?
My original plan is using 2 9V batteries in series to create 18V and using a voltage divider to divide it into 6V and 12V, and using 6V to power the rest of the circuit. If the voltage drop stated in 1 is actually caused by the protection of 9V batteries, is there any way to bypass it?